Continuous casting machine



April 18, 1967 c AUNDERS ETAL 3,314,115

CONTINUOUS CASTING MACHINE Filed Jan. 17, 1964 3 Sheets-Sheet 1 Fig.7 Fig.2 N7 Al32 1; 1911 A3 0 0 I 2 8 8 A ril 18, 1967 Filed Jan. 17, 1964 5 Sheets-Sheet z April 1967 c. w. SAUNDERS ET AL 3,314,115

CONTINUOUS CASTING MACHINE Filed Jan. 17, 1964 5 Sheets-Sheet 5 l I l l I T I United States Patent 3,314,115 CONTINUOUS CASTING MACFHNE Charles Wilfrid Saunders, Aspatria, Cumberland, England, and Armin Thalmann, Zurich, Switzerland, assignors to Concast AG., Zurich, Switzerland Filed Jan. 17, 1964, Ser. No. 338,464 7 Claims. (Cl. 22-57.2)

This invention relates to continuous casting apparatus and, more particularly, relates to improved continuous casting apparatus having improved structure for strand deflection, which structure comprises at least one pair of withdrawal rollers, arranged for rotating movement in bearings, a bending roller following this pair of withdrawal rollers, and a counteracting roller.

In the continuous casting apparatus known to the art, a water cooled open ended vertical mould is provided into which molten metal is poured. The molten metal is formed into a strand by the mould by forming a skin about the molten core. The cooling effect of the mold is sufiicent so that the skin thickness is sufficient to contain the molten core and the strand is guided in a roller apron into a secondary cooling zone for additional cooling. The strand is withdrawn by means of withdrawal rollers, bent to the horizontal line by means of a bending device, and straightened afterwards. This bending of the strand allows cutting in the horizontal line, thus, reducing the total height of the plant. Furthermore, the danger of cutting into the liquid core is reduced.

This known arrangement has the disadvantage that the forces resulting from the bending of the strand are imposed upon the withdrawal rollers. The magnitude of such forces necessitate heavy design of the withdrawal rollers and their bearings. This in turn requires much space and expensive construction. Further, such construction has the additional disadvantage in multistrand casting apparatus, of making the distances between strand centers longer, elongating the length of feeding launders for the molten metal, and, in turn causing greater cooling of the liquid steel during feed to the mold.

In an attempt to reduce the magnitude of forces on the withdrawal rolls caused by the bending, the art provided a counter-acting roller on the opposite side of the strand from the bending roller. However, in such arrangement, the strand can be compared to a double-arm lever, turning around the counter-acting roller. The bending roller is acting upon the first arm of this double-arm lever and the withdrawal roller upon the second arm. To keep the total machine height as low as possible, the arms of this lever are very short. Therefore, a considerable force must be applied onto the strand by the bending roller to ensure the bending of the strand, also producing a considerable reaction force on the withdrawal rollers. reaction on the counter roller is the sum of the said forces. It has now been learned that these intense forces cause deformation of the hot strand. A further disadvantage is that not only one roller of a pair of withdrawal rollers, but one roller in each of the two pairs of withdrawal rollers is stressed by the force caused by the bending. Thus, the system of the forces is statically undefined.

A further disadvantage of the force of reaction admitted to the withdrawal rollers is the unequal application of force to the corresponding withdrawal rollers, thus, causing unequal stress on the gear box or on the motor with single drive of the withdrawal rollers. This unequal loading of the withdrawal rollers causes unequal friction conditions between each single withdrawal roller and the strand, thus, causing unequal wear.

It is the objective of this invention to avoid these disadvantages and to achieve with practically equal total height of the machine an advantageous distribution of the forces originating in the bending. This is achieved by The force of movable mounting of the bearings of at least one pair of withdrawal rollers, transversely to the axis of the strand and the axis of the rollers. This movable bearing ensures that at least one pair of withdrawal rollers is kept free of forces originating in the bending of the strand, thus, only driving the strand.

This invention is described in detail in the following portion of the specification, which may best be understood by reference to the accompanying drawings, of which:

FIG. 1 is a side elevation view, partially in schematic form of the apparatus constructed in accordance with the present invention.

FIG. 2 is a side elevation, in schematic form, of another embodiment employing a counter-acting roller.

FIG. 3 is a side elevation, in schematic form, of still another embodiment of this invention.

FIG. 4 is a partially sectioned side elevation to enlarged scale of another embodiment of this invention, taken along lines IVIV of FIG. 5.

FIG. 5 is a partially sectioned front elevation view of the apparatus shown in FIG. 4.

FIG. 6 is a schematic view illustrating the use of the principle according to FIG. 4 for the straightening of the strand, and

FIG. 7 is a partially sectioned elevation in schematic form, of still another embodiment of this invention.

In FIG. 1, there is shown strand 1, issuing from a continuous casting mold, which is withdrawn by withdrawal rollers 2, 3, 4 and 5. The withdrawal rollers 2 and 3 form a pair of withdrawal rollers A, the withdrawal rollers 4 and 5 form a pair of withdrawal rollers B. All with drawal rollers are positively driven by drive arrangements known to the art and, thus, not illustrated to avoid obscuring of the present invention. The withdrawal rollers 2 and 3 are arranged in bearings 6 and 7 for rotation. The bearings 6, 7 are fixed to a frame 8, which comprises wheels 9 running on rails 10 connected to the structure. The bearings 6, 7 are movably arranged on frame 8 for adjustment of the withdrawal pressure. The withdrawal pressure is adjusted by an adjusting device 12 and by means of springs 11. The adjusting device 12 is connected to a support 13 which is fixed to the frame 8. The rotating mounted withdrawal rollers 4 and 5 are connected to the structure of the strand by means of bearings 14 and 15. The bearing 14 is provided with an adjusting device 12 to adjust the withdrawal pressure in the manner of bearing 7. The bending roller 16 is rotatably mounted on a lever 17 actuated by a plunger 18.

In the arrangement of the prior art, ment originating by the bending roller 16 is transmitted by the strand 1, used as a lever turning around the counter-acting roller 5 to the withdrawal roller 2 which is, in this case, fixed to the structure, thus, admitting the forces of this moment to the withdrawal roller 2 and 5, and causing the above mentioned disadvantages.

However, according to the present invention, the withdrawal rollers 2 and 3 form together with the bearings 6 and 7 the frames 8 and 13 and the adjusting device 12, a unit 19, movable on wheels 9, and the withdrawal roller 2 is kept free of any force of reaction. This reaction force may, for example, be taken up by a roller apron (not shown), which force is much lower in magnitude since the roller apron is above the withdrawal roller and, thus, operation over a longer lever arm. Because the reaction forces are lower on the longer lever arm, the

the bending moroller apron can be of conventional size and strength,

reinforcement being unnecessary.

The releasing of the pair of withdrawal rollers A from the forces, caused by the bending of the strand, permits a substantially lighter design of the respective withdrawal rollers and of the drive arrangement.

To permit a perfect introduction of the dummy bar 3 between the withdrawal rollers 2 and 3, the unit 19 is kept in position by springs 20 which ensure that the middle of the distance between the withdrawal rollers 2 and 3 is aligned with the axis of the mold. The springs 20 may be detachably mounted to permit fast withdrawal of the unit 19, if due to a breakdown, or changing of the cross-section, a rapid change of the unit is necessary.

According to the example of FIG. 2, a separate counter-acting roller 22 is arranged as a fulcrum for the bending. The pair of withdrawal rollers B is mounted movably and constructed according to the unit 19, whereas the pair of withdrawal rollers A is constructed according to the pair of withdrawal rollers B shown in FIG. 1. All four withdrawal rollers are positively driven as shown by traverse diameter lines. This symbol is also used for the further schematic figures. The bending roller 16 and the counter-acting roller 22 are not positively driven. By the movable arrangement of the pair of withdrawal rollers B, the withdrawal roller 4 is kept free of forces caused by bending. These forces are received by the withdrawal roller 2 of the pair of withdrawal rollers A. Therefore, this roller 2 may also be called supporting roller. By the arrangement of the special counter-acting roller 22, the lever arm formed by the strand 1 between the withdrawal roller 2 and the counter-acting roller in respect of the one shown in FIG. 1 is elongated. Thus, the admission of forces on the withdrawal roller 2 is considerably reduced so that no essential reinforcement of the construction is necessary.

According to the example shown in FIG. 3, a separate counter-acting roller 23 and a separate supporting roller 24 are arranged. The lever arm between the counteracting roller and the supporting roller in this embodiment is much longer compared with the system of FIG. 2, so that to the supporting roller 24 and the counter-acting roller 23, smaller forces are applied. The pairs A and B of withdrawal rollers are mounted movably and, therefore, entirely free of forces originating in the bending, and they are only used for the withdrawing of the strand. The withdrawal roller 3 as a corresponding roller t the Withdrawal roller 2 does not need to be positively driven, but it is pressed by the withdrawal pressure to the strand 1. Thus, it is possible to drive the counter-acting roller 23 positively, as the conditions of friction due to the vertical pressure of the strand on roller 23 is high on this roller. Such a drive is quite easy as instead of the withdrawal roller 3, the counter-acting roller 23 is driven by a common drive of the withdrawal rollers.

According to FIGS. 4 and 5, both pairs of withdrawal rollers A and B are arranged movably. The strand 1 is bent by the bending roller 16, which is connected to a lever 30 mounted on a support 32 of the structure and :arranged for pivoting around a bolt 31 by a plunger 34, around a counter-acting roller 26, arranged between the two pairs of withdrawal rollers A and B. The movement of the plunger 34 is controlled by the fluid controlla'bly introduced through pipes 35 and 36. The counter-acting roller 26 is fixed in position by a frame .37 and is positively driven instead of the withdrawal roller 5. The supporting roller 24 is, as shown in FIG. 3, :arranged above the pair of withdrawal rollers A in a supporting structure 38 which is zfixed to the frame 37. An advantage of this arrangement is that the lever arm between the bending roller 16 and the counter-acting roller 26 as well as the lever arm between the counteracting roller 26 and the supporting roller 24 are very long. Thus, the pressures imposed by the rollers on the strand are correspondingly reduced.

The withdrawal rollers 2 and 3 are arranged in bearings 39, 40 in a frame 41 and guided laterally by rods 42. Each bearing 40 is coupled by a spring 43 with an adjusting device 44, comprising a handwheel. This adjustment is used for the regulation of the pressure, for pressing the withdrawal rollers onto the strand, and also for the adjustment of the Strand thickness. Each frame 37 4 comprises projections 45 which are guided by rods 45, fixed to the casing 38. To ensure that the middle of the distance between the withdrawal rollers 2 and 3 in the state of rest is aligned with the axis of the mold, equally laid-out springs 47 are arranged for adjustment.

At the pair of withdrawal rollers B, the identical elements are marked with the same numbers as at the pair of withdrawal rollers A. As the pair of withdrawal rollers B is arranged in the area of the bent strand in order to receive better conditions for withdrawing, it is fixed in the center axis of the bending radius and is tilted so that the rollers are positioned astraddle the strand along a substantial line transverse to the strand axis.

The withdrawal rollers 2 and 3 are positively driven by trans-mission rods 50 by a conventional drive arrangement. The counter-acting roller 26 is positively driven by a transmission rod 5 1, and the withdrawal roller 4 by a transmission rod 52 by a further drive.

This arrangement according to FIGS. 4 and 5 shows the advantage with multi-stranding that the long distance between the two pairs of withdrawal rollers A and B permits an arrangement above each other of the drives of neighboring withdrawal roller sets, thus, reducing the distances between the strands and the length of the feeding pipes for the liquid steel considerably. This long distance between the pairs of withdrawal rollers A and B would result in a disadvantageous increase of height of the machine. In order to avoid this, the pair of withdra-wal rollers B is, as mentioned above, arranged in the arc of the bent strand.

The principle according to the invention can be used not only for the bending of the strand, but also for the analogous straightening. As in the former examples, the withdrawing and the bending is effected by the same device, the withdrawing and the straightening is also effected by the same device. In FIG. 6, the principle of FIG. 4 is changed for straightening. The difference between these figures is that one movable pair of withdrawal rollers is omitted, and to the counter-acting roller 26' as Well as to the bending roller 16' a corresponding roller is added. The supporting roller 24 is arranged in the bent area of the strand 1. This roller is followed by the positively driven counter-acting roller 26'. As corresponding roller, a positively driven roller 55 is arranged. The withdrawal rollers 4' and 5' of the mov ably arranged pair of withdrawal rollers B are positively driven. For permitting use of the device for different sizes of the strand, the supporting roller 24, the rollers 55 and 5' can be adjusted. To the bending roller 16', a supporting roller 56 is arranged as corresponding roller. The rollers 24', 26' and 16 are for straightening, whereas the rollers 55, 26', 5 and 4 are for the withdrawing of the strand.

As shown in the former figures, the mobility of a pair of withdrawal rollers is achieved by mechanical means. This mobility can also be achieved by hydraulic means, as shown in FIG. 7. The withdrawal rollers 4 and 5 of a movable pair of withdrawal rollers are arranged as known to the art. The bearings on each side of the withdrawal rollers are connected by rods 60 to plungers 61, arranged in cylinders 62 and 63. Cylinder 62 is connected by one pipe 64, comprising a nonreturn valve and a bypass valve to an oil pressure container 66. Cylinder 63 is provided with a conduit 67, which is connected to the conduit 64 of cylinder 62.

Each plunger 61 is biased by a spring 63 which ensures alignment to the mold axis with the middle between the withdrawal rollers 4 and 5 in the state of rest. Projections 69 fixed to the bearings make it impossible that the withdrawal rollers 4 and 5 get too near to each other by the pressure of the springs 68.

By the said arrangement of the communicating pipes 64 and 67, the pressure of the strand against the withdrawal roller 4 causing a pressure difference between the cylinders 62 and 63, is transposed by means of the plungers 61 of the cylinder 62 and the pressure medium in the conduits 64 and 67 of the cylinder 63. Thus, the withdrawal roller 4 is moving in the direction of the plunger until the pressure diflference is equalized. For the discharge of the plunger 61, the pressure in the container 66 is first released and then the bypass valve is opened.

This invention may be variously modified and embodied within the scope of the subjoined claims.

What is claimed is:

1. A continuous casting machine for casting a continuous initially substantially vertical strand comprising at least one pair of rotatably driven withdrawal rollers, a strand bending roller, 21 counteracting roller, said strand bending roller and said counteracting roller being positioned at spaced apart locations along said strand, said strand bending roller being movable to exert a bending moment by cooperation between said strand bending roller and said counteracting roller to bend said cast strand, the axial displacement between said strand bending roller and said counteracting roller being short, and support roller means positioned above said ithdrawal rollers and on the same side of said strand as said bending roller and displaced from said bending roller and said counteracting roller by a distance which is long as compared with the axial displacement between said strand bending roller and said counteracting roller, said pair of withdrawal rollers being movazbly mounted for movement transversely of the axis of said strand and the axis of said roller so that the reaction forces of said bending are imposed upon said supporting roller means and are not imposed upon said Withdrawal rollers.

2. A continuous casting machine in accordance with claim 1 in which said supporting roller means comprises a supporting roller.

3. A continuous casting machine in accordance with claim 1, which includes two pairs of withdrawal rollers spaced apart along the strand and in which said counteracting roller is arranged between the two pairs of withdrawal rollers.

4. A continuous casting machine in accordance with claim 1, in which each withdrawal roller is mounted in a bearing, in which said bearings are slidably mounted within said machine for sliding movement transversely of the strand axis, and which includes means for adjustably urging said rollers into contact with said strand.

5. A continuous casting machince in accordance with claim 2, in which at least one pair of withdrawal rollers is tilted to position the rollers astraddle the bent strand.

6. A continuous casting machine in accordance with claim I, which includes spring mean to align the center of the gap between the rollers of one pair of withdrawal rollers with the axis of the strand.

'7. A continuous casting machine in accordance with claim 1, which includes hydraulic piston means to deflect each roller of a pair in the same direction and with the same amount.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Iron and Steel Institute Journal, vol. 191, 1959, page 129.

J. SPENCER OVERHOLSER, Primary Examiner. R. S. ANNEAR, Assistant Examiner.

February 

1. A CONTINUOUS CASTING MACHINE FOR CASTING A CONTINUOUS INITIALLY SUBSTANTIALLY VERTICAL STRAND COMPRISING AT LEAST ONE PAIR OF ROTATABLY DRIVEN WITHDRAWAL ROLLERS, A STRAND BENDING ROLLER, A COUNTERACTING ROLLER, SAID STRAND BENDING ROLLER AND SAID COUNTERACTING ROLLER, SAID STRAND TIONED AT SPACED APART LOCATIONS ALONG SAID STRAND, SAID STRAND BENDING ROLLER BEING MOVABLE TO EXERT A BENDING MOMENT BY COOPERATION BETWEEN SAID STRAND BENDING ROLLER AND SAID COUNTERACTING ROLLER TO BEND SAID CAST STRAND, THE AXIAL DISPLACEMENT BETWEEN SAID STRAND BENDING ROLLER AND SAID COUNTERACTING ROLLER BEING SHORT, AND SUPPORT ROLLER MEANS POSITIONED ABOVE SAID WITHDRAWAL ROLLERS AND ON THE SAME SIDE OF SAID STRAND AS SAID BENDING ROLLER AND DISPLACED FROM SAID BENDING ROLLER AND SAID COUNTERACTING ROLLER BY A DISTANCE WHICH IS LONG AS 